import { Injectable, Injector } from '@angular/core';
import { Router } from '@angular/router';
import { HttpInterceptor, HttpRequest, HttpHandler, HttpErrorResponse,
         HttpSentEvent, HttpHeaderResponse, HttpProgressEvent, HttpResponse, HttpUserEvent,
       } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import { of } from 'rxjs/observable/of';
import {  throwError } from 'rxjs';
import { ErrorObservable } from 'rxjs/observable/ErrorObservable';
import { mergeMap, catchError } from 'rxjs/operators';
import { NzMessageService } from 'ng-zorro-antd';
import { _HttpClient } from '@delon/theme';
import { environment } from '@env/environment';

/**
 * 默认HTTP拦截器，其注册细节见 `app.module.ts`
 */
@Injectable()
export class DefaultInterceptor implements HttpInterceptor {
    constructor(private injector: Injector) {}

    get msg(): NzMessageService {
        return this.injector.get(NzMessageService);
    }

    private goTo(url: string) {
        setTimeout(() => this.injector.get(Router).navigateByUrl(url));
    }

    private handleData(event: HttpResponse<any> | HttpErrorResponse): Observable<any> {
        // 可能会因为 `throw` 导出无法执行 `_HttpClient` 的 `end()` 操作
        this.injector.get(_HttpClient).end();
        let test = event.status;
        
        // 业务处理：一些通用操作
        switch (test) { // event.status
            case 200:
                break;
            case 401: // 未登录状态码 
            case 40101:
            case 40131:
                this.msg.warning('你已被登出,请重新登录');
                this.goTo('/passport/login');  
                break;
            case 403:
                // this.msg.error('权限拒绝');
                return throwError({status: 500, message: event['error']['message']}); //Observable.throw
            case 404:
            case 420:
            case 500:
            case 30101:
                //this.goTo(`/${event.status}`);\                                               
                return throwError({status: 500, message: event['error']['message']}); //Observable.throw
        }              
        return of(event);
    }

    intercept(req: HttpRequest<any>, next: HttpHandler):
        Observable<HttpSentEvent | HttpHeaderResponse | HttpProgressEvent | HttpResponse<any> | HttpUserEvent<any>> {

        // 统一加上服务端前缀
        let url = req.url;
        if (!url.startsWith('https://') && !url.startsWith('http://')) {
            url = environment.SERVER_URL + url;
        }

        const newReq = req.clone({
            url: url
        });
        
        return next.handle(newReq).pipe(
                     mergeMap((event: any) => {
                         // 允许统一对请求错误处理，这是因为一个请求若是业务上错误的情况下其HTTP请求的状态是200的情况下需要
                     if (event instanceof HttpResponse && event.status === 200)
                             return this.handleData(event);
                     // 若一切都正常，则后续操作
                         return of(event);
                     }),
                     catchError((err: HttpErrorResponse) => this.handleData(err))
                );
    }
}
